Jeffco Invasive Species Management

Fall 2026 Mountain Pine Beetle Landowner Assistance Program
Applications for owners of 40+ acres due Nov 5, 2026
www.jeffco.us/jcism

Mountain Pine Beetle Monthly Tips - October 2026

The number of sites affected by mountain pine beetle (MPB) within the county has increased significantly since 2025. This fall is a good time to start looking for newly infested trees.

Look for:
• Frass - sawdust -like material at the base of trees or in the crevices of bark
• Pitchtubes – orangish-pink, popcorn shaped accumulation of sap on the trunk of the tree
• Feeding galleries – Adults form vertical feeding galleries under the bark that are usually filled with frass

Remember - The trees that faded and turned red this season have died. They are no longer at risk of spreading MPB because the adult beetles that matured over the summer have already left those trees.

Mountain Pine Beetle Monthly Tips - September 2026
We are seeing an expansion of MPB within the county. To get ahead of the issue, start planning your fall and winter MPB mitigation efforts now.

Conducting your survey this fall will help you identify areas affected by MPB and prepare for mitigation before beetles emerge next year.

What You Can Do:

• Identify any areas on your property with newly faded trees and search the green trees nearby for signs of attack.

The trees that faded and turned red this season have died. They are no longer at risk of spreading MPB because the adult beetles that matured over the summer have already left those trees.

• Develop a plan for mitigating any MPB found in the newly infested trees.

Adult females have recently laid their eggs which will soon hatch into larvae that will overwinter under the bark. Early next summer the larvae will transform to pupae and then emerge as adults next summer.

• Remember - Areas where trees have been removed may be seeing noxious weeds starting to grow. Fall is a good time to treat those weeds.

Learn more at www.jeffco.us/jcism

Please - Don't Move Beetle Wood
Transporting logs that contain this year's adult mountain pine beetles (MPB) (that have not yet emerged) can spread the beetles to new sites. Please don't move infested "Hot" logs during the MPB flight period June 15 through Oct 1.

MPB Monthly Tips

MPB adults have begun their flight for the season which will run through the middle of September.

We are finding that residents may not be familiar with the beetle’s lifecycle and when it is the best time to manage the beetles. Below are three myths and their associated truths to help clear up the misconceptions.

3 MPB Myths

Myth 1
Cutting down trees that have turned red controls the beetle.

Truth
Once your trees have started to fade, it is too late to control this generation of MPB. The best time to mitigate MPB is between October to early June, before the beetle matures into an adult. Trees that have turned red no longer contain the beetle and are not a risk of spreading it.

Myth 2
Faded red trees are an increased fire risk.

Truth
According to CSFS, all pine trees along the Front Range are in a high-risk fire zone and standing dead pine trees do not pose a larger risk for igniting a fire.
Read more about MPB and fire risk within the Front Range. https://csfs.colostate.edu/2026/05/18/mountain-pine-beetle-outbreaks-and-changes-to-wildfire-risk-and-behavior-in-ponderosa-pine-forests-on-the-colorado-front-range/

Myth 3
Spraying my trees in July and August is the best timing.

Truth
Treating in July or August is too late. If you are going to have your trees sprayed for MPB, you need to time it between May and mid-June, before the adults emerge. Treatment should only have to be done once a year for MPB.

Visit our website www.jeffco.us/jcism to learn more about MPB, how to identify infestations, and available control options.

MPB Monthly Tips – July
Adult mountain pine beetles (MPB) are completing their development beneath the bark of infested pine trees. They are beginning to emerge and are flying in search of new host trees. Beetle flight typically continues through early to mid-September.

What to Expect
Pine trees infested last year are beginning to fade and will gradually change to red. Although these red trees are a visible sign of past infestation, they no longer pose a risk of spreading MPB once the new adults have emerged.

Remember
Once adult beetles begin to emerge, treatments are no longer effective. The best time to treat infested trees is between October to early June.

Visit our website https://www.jeffco.us/2738/Mountain-Pine-Beetle to learn more about MPB, how to identify infestations, and available control options.

Slash Site Update 🌲

We’ll be continuing the pilot hours at the Slash Site for the next few months. Thanks to everyone who has shared feedback so far—keep an eye out for another survey coming soon!

🚫 Hot logs will not be accepted July 15 – September 15
(“Hot logs” contain Mountain Pine Beetle larvae.)

This helps reduce the spread of beetles and protect our local forests.

Thank you for helping keep Gilpin County healthy and resilient!

Visit the Transfer Station & Slash page for more information: https://link.orlo.us/Gt3E6